jobs argument for ghc make

For some reason ghc eats a lot of system time in that mode. Likely jobs without arguments is not very good idea and i’ll need to limit it by minimum of MAKEOPTS value and some N (Cabal picked 64).

Even in this mode 2-time speedup is visible on large packages.

So what did break?

Not _that_ much, actually.

alex and happy generated parsers

All package maintainers who ship lexers generated by alex and parsers generated by happy are strongly advised to update those tools locally and reissue hackage update, as old parsers do not compile against ghc-7.8.

If you have happened to use low-level

(==#) ::Int#->Int#->Bool

primitives, you might need to port your code a bit, as how their type is a bit different: